Various downhole well configurations, including vertical, directional, or horizontal, are used in oil and gas production from subterranean formations. With reference to FIG. 1 (PRIOR ART), horizontal wells W typically comprise a relatively vertical section V (which may be vertical or off-vertical) and a relatively lateral section L (which may or may not be horizontal) that are connected by a curved ‘build’ section, often referred to as the ‘heel’ H. In almost all cases, the lateral section is the productive target of the well and will be configured to allow the inflow of fluids (oil/water/gas) from the reservoir into the wellbore. The configuration of horizontal wells often results in a complex interaction or interference between liquids and gas within the lateral and heel sections L,H, compounded by the fact that the lateral section L will often undulate significantly along its overall trajectory.
For example, horizontal wells can have sub-hydrostatic flowing reservoir pressures that require artificial lift systems to produce the well, but conventional lift systems, such as pumps, gas lifts, or plunger lifts are not suited for installation deeper than the H section of the well (i.e. into the L section of the well). Due to the size constraints, artificial lift systems can often only be positioned in the wellbore near or above the heel section H (FIG. 1, PRIOR ART). When artificial lift systems are not positioned within the productive target area, the resulting inflow of fluids becomes inconsistent, with the majority of the produced fluids coming from near the heel section H and less coming from the target lateral section L.
Problems arise when the positioning of a pump P creates higher inflow drawdown from the areas of the reservoir closest to the heel H of the well (e.g. drainage area “A” in FIG. 1) and less inflow drawdown towards the toe T of the well. Even where smaller pumps, such as jet pumps, have been extended to be near the mid-point of the lateral section L, substantial flow interference arises because as production progresses over time, gas G flowing upwardly towards the vertical V section travels against the liquids O flowing downwardly towards the pump P intake (FIG. 2, PRIOR ART). For instance, oil, water, and gas generally flow in the direction from the toe T section of the well to the pump P′ intake location; however, in the portion of the well between the pump P location and the heel H section, gas flows in the opposite direction from the flow of liquids (i.e. oil and/or water). Flow interference arises when the gas G flow winds up sweeping a significant volume of liquid O up into the vertical V section of the well. This refluxing volume of liquid O and gas G results in an artificially high flowing bottom hole pressure, which limits the ultimate inflow rate of the well. Consequently, flow interference is undesirable because it diminishes the efficiency of the system. Further, problems arise when sand and other solids drop out of the produced fluid and build up, plugging the wellbore.
Therefore, there is a need for a well production system that overcomes the above-noted problems.